The miniaturization of pacemakers and other implants

Researchers at Stanford University have created a millimeter-sized, wirelessly powered implanted cardiac device.

“Previous mathematical models indicated that low-frequency transmitters and large antennas, too large to be practical for implantable devices, would be necessary for wireless power within the body. The researchers have shown now that high-frequency wireless power transmission to a device in the human body is possible at much deeper depths within the body than previously thought. An important advantage of this is that higher frequency waves can work with smaller coils on the receiving device.

With the new method, optimal power transmission happens at 1.7GHz, at a rate about 10 times more efficiently than earlier devices and with a receive antenna 10 times smaller than previous ones. The images above show power delivery to the human heart from a 200MHz low-frequency transmitter (left) and a 1.7GHz high-frequency transmitter (right), showing focusing of power on the heart in the right image. This way a millimeter-radius coil could harvest over 50 microwatts of power. The researchers think their solution could potentially be used for virtually any medical applications for which device size and power matter, including swallowable pillcams, permanent pacemakers and precision brain stimulators.”